Question

I am thinking of a number. when it is increasd by 7, it equals 21. what is my number

a. n=28

b. n=14

c. n=7

d. n=147

Answer 1

if X is increased by 7 to make 21
X + 7 = 21
then rearrange the equation to get X
X = 21-7
X = 14(b)

Answer 2

Let the number be x;
x+7=21
Subtracting 7 from each side,
x+7-7=21-7
x=14