If 3 is added to a number and the sum is tripled, the result is 21 more than the number. Find the number

9

Step-by-step explanation:

If 3 is added to the number: x + 3

b) ...and the sum is tripled..

"The sum" is "x + 3" so: 3(x+3)

c) ...the result is 27 more than the number.

27 more than the number is x + 27

d) Put it all together:

3(x + 3) = x + 27

Solve for x:

1) Distribute the left side of the equation:

3x + 9 = x + 27

2) Subtract x from each side of the equation:

2x + 9 = 27

3) Subtract 9 from each side of the equation:

2x = 18

4) Solve for x:

x = 9

Check:

1) x = 9

2) 3(x + 3) = x + 27

3) 3 ([9] + 3) = [9] + 27

4) 3(12) = 9 + 27

5) 36 = 36

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.