There are 270 students in Year 7 Each student studies one of French or German or Spanish.

Of these 270 students

2

study French

9

the number who study French : the number who study Spanish = 3:7

42 boys study German

Of the students who study German, what percentage are boys?

You must show your working.

4a. is 3 miles every hour

4b. is 1/3 of an hour per mile

step-by-step explanation:

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

the first option is the answer.