Alex weighs 85 pounds. Together, he and his sister weigh ten pounds more than five times the weight of his sister. What is the weight, w, of Alex's sister?
A) 85 + w=5w - 10; 25lb
B) 85 + w - 10=5w; 7.5lb
C) 85 + w=5w; 28lb
D) 85 + w=5w + 10; 15lb
Let's set up the equation to solve for the weight of Alex's sister:
85 + w = 5w + 10
Subtract 5w from both sides:
85 + w - 5w = 5w - 5w + 10
85 - 4w = 10
Subtract 85 from both sides:
85 - 85 - 4w = 10 - 85
-4w = -75
Divide by -4:
-4w/-4 = -75/-4
w = 18.75
So, the weight of Alex's sister is 18.75 pounds. The answer is not one of the provided options.