90 juniors took different sat-ii tests. 40% more students took chemistry than history, and 50% more students took math than chemistry. how many students took each test?
students took history test
took chemistry test
took math test

20 Students took History Test

28 Students took Chemistry Test

42 Students took Math Test

Step-by-step explanation:

Let

x > Students that took History Test

y ---> Students that took Chemistry Test

z > Students that took Math Test

we know that

x+y+z=90 > equation A

y=1.40x > x=y/1.40 > equation B

z=1.50y > equation C

substitute equation B and equation C in equation A and solve for y

(y/1.40)+y+1.50y=90

Multiply both sides by 1.40

y+1.40y+2.1y=126

4.5y=126

y=28

Find the value of x

x=y/1.40 > x=28/1.4=20

Find the value of z

z=1.50y > z=1.50(28)=42

therefore

20 Students took History Test

28 Students took Chemistry Test

42 Students took Math Test

£56

step-by-step explanation:

u divide 24 by 3 and u get 8 so if u do 8 time 7 or 8+8+8+8+8+8+8 u get 56 and 56 divided by 7 is 8.

a.   we have two

lines:   y = 4-x   and  

y = 8-x^-1

given two simultaneous equations that are both to be

true, then the solution is the points where the lines cross. the intersection is

where the two equations are equal. therefore the solution that works for both

equations is when

4-x = 8-x^-1

this is where the two lines will cross and that is the

common point that satisfies both equations.

b.   4-x = 8-x^-1

  x           4-x       8-x^-1

-3           7        

8.33

-2           6         8.5

-1           5         9

  0           4        

-

  1           3        

7

  2           2        

7.5

  3           1         7.67

the table shows that none of the x values from -3 to 3 is

the solution because in no case does

4-x = 8-x^-1

to find the solution we need to rearrange the equation to

find for x:

4-x = 8-x^-1

multiply both sides with x:

4x-x^2 = 8x-1

x^2+4x-1=0

x= -4.236, 0.236

therefore there are two points that satisfies the

equation.

find y:  

x=-4.236

y = 4-x   = 4 – (-4.236)

= 8.236

y = 8-x^-1 =   .236)^-1

= 8.236

x=0.236

  y = 4-x   = 4 – (0.236) = 3.764

y = 8-x^-1 =   8-(0.236)^-1

= 3.764

thus the two lines cross at 2 points:

(-4.236, 8.236) & (0.236, 3.764)

c.   to solve

graphically the equation 4-x = 8-x^-1

we would graph both lines: y = 4-x   and   y

= 8-x^-1

the point on the graph where the lines cross is the

solution to the system of equations.

just graph the points on part b on a cartesian coordinate

system and extend the two lines.   the

solution is, as stated, the point where the two lines cross on the graph.

step-by-step explanation:

mark brainliest!