Question

1. Suzette ran and biked for a total of 34 mi in 3.5 h. Her average running speed was 6 mph and her average biking speed was 12.5 mph. Let x = total hours Suzette ran. Let y = total hours Suzette biked. Use substitution to solve for x and y. Show your work. Check your solution. (a) How many hours did Suzette run? (b) How many hours did she bike? Answer:

Answer 1

answer

First we need to write system of 2 equations with 2 variables:

x*6 + y*12.5 = 34

x+y = 3.5

for substitution we express one of variables in one of equations and put it in other equation.

x = 3.5-y

(3.5 - y)*6 + 12.5*y = 34

21 - 6y + 12.5y = 34

6.5y = 13

y = 2

x = 3.5 - y = 3.5 - 2 = 1.5

she ran for 1.5 hours and biked for 2 hours.

check:

1.5*6 + 2*12.5 = 9 + 25 = 34 = 34