Question

Sarah is twice as old as her youngest brother if the difference between their ages is 15 years how old is her youngest brother

Answer 1

2x - x = 15
x = 15 yr, age of the youngest brother

Answer 2

s=sarah age
b=brother age
s= 2 times b
s=2b

if difference beteeen ages is 15
sarah is older so
s-b=15

we now have
s=2b
s-b=15

since s=2b
sub 2b for s in othe equaiton
2b-b=15
b=15
wow, that's easy


brother is 15 years old