Answer: Suzette ran for 2 hours and biked for 2 hours.
Step-by-step explanation:
Let x = total hours Suzette ran.
Let y = total hours Suzette biked.
She spent a total of 4 hours. It means that
x + y = 4
Distance = speed × time
Her average running speed was 5 mph. This means that distance covered while running is 5x
Her average biking speed was 15 mph. This means that distance covered while biking is 15y.
Suzette ran and biked for a total of 40 miles. It means that
5x + 15y = 40- - - - - - - - - - - - -1
Substituting x = 4 - y into equation 1, it becomes
5(4 - y) + 15y = 40
20 - 5y + 15y = 40
- 5y + 15y = 40 - 20
10y = 20
y = 20/10
y = 2
x = 4 - y = 4 - 2
x = 2