First we'll substitute
with 

Then we can separate this.

Then we'll solve this.



Then we'll plug in to find the extraneous solutions (if any)

Given that Collins made 15% down payment, the amount to be financed will be given by:
(Price of treadmill)-(down payment)
down payment=15/100×1662
=$249.3
thus the amount to be financed will be:
1662-249.3
=$1412.7
None of them are correct.
Let Daniel's age be 'x' years , hence, Lisa's age is (x - 5) years. Let Grandma's age be 'y' = 54 years.
Hence,
x(x - 5) = 2/3 × y
x² - 5x = 2 × 54 years / 3
x² - 5x = 36 years
x² - 5x - 36 = 0
∆ = (-5)² - 4(1)(-36) = 25 + 144 = 169
√∆ = √169 = 13

x1 = (5+13)/2, x2 = (5-13)/2
x1 = 9, x2 = -4
Since, age can't be negative,
Daniel's age = x = 9 years.