Question

The price of commodity a is 4500 and increases at the rate of $6 every three months. Commodity b costs $5400 and increases at rate of $2 every four months. How many years will it take for the two commodities to be equal?

Answer 1

Let x be the months and y be the cost.

Rate of increase of commodity A = 6/3 = $2 per month
Equation:
y = 2x + 4500

Rate of increase of commodity B = 2/4 = $0.5 per month
Equation:
y = 0.5x + 5400

Equating the costs,
2x + 4500 = 0.5x + 5400
1.5x = 900
x = 600 months
x = 600 / 12 = 50 years