Respuesta :

Use the distributive property.

1/7(105 + r) = 20
15 + (1/7)r = 20

Then subtract each side of the equation by 15.

15 + (1/7)r = 20
(1/7)r = 5

Divide both sides by 1/7.

(1/7)r = 5

r = 35

So, the answer to this question is r is equal to 35.