Guy rented the concrete mixer for 7.5 hours
Solution:
Guy is pouring a new patio for his house
He rents a concrete mixer for $50 per day plus $12.50 per hour
Let "x" be the number of hours mixer is rented for
He is charged $143.75
Total charge = $ 143.75
From the given information, we frame a equation as,
Total charge = $ 50 per day + $ 12.50 per hour
143.75 = 50 + 12.50(number of hours)
143.75 = 50 + 12.50x
Solve the equation for "x"
12.50x = 143.75 - 50
12.5x = 93.75
x = 7.5
Thus he rented the concrete mixer for 7.5 hours