Jeannie is 8 years older than her younger sister April. When added together, their ages equal 198. How old is April?

"Jeannie is 8 years older than her younger sister April"

this translates to

J = A + 8

"added together, their ages equal 198"

this translates to

A + J = 198

Plug the first equation into this one and we get

A + A + 8 = 198

add like terms

2A + 8 = 198

subtract 8 from both sides

2A = 190

divide both sides by 2

A = 190/2 = 95

Therefore April is 95 years old