Gmat_mission wrote: ↑

Sun Nov 28, 2021 7:20 am

At Joe's candy store, the total cost of \(1\) gumball and \(1\) lollipop is \(\$0.74.\) The total cost of \(1\) chocolate bar and \(1\) lollipop is \(\$0.92.\) The total cost of \(1\) gumball and \(1\) chocolate bar is \(\$1.24.\) What is the cost in dollars of \(1\) chocolate bar?

A. 0.53
B. 0.59
C. 0.63
D. 0.67
E. 0.71

Answer: E

Source: Magoosh

We can solve this question using three variables or one variable.
Since the other posters used three variables, let's use one variable.

We're asked to find the cost of one chocolate bar.
So, let's let c = the cost of one chocolate bar (in dollars)

The total cost of 1 chocolate bar and 1 lollipop is $0.92.
So, the cost of 1 lollipop = $0.92 - (the cost of 1 chocolate bar)
In other words, the cost of 1 lollipop = 0.92 - c

The total cost of 1 gumball and 1 lollipop is $0.74.
So, the cost of 1 gumball = $0.74 - (the cost of 1 lollipop )
In other words, the cost of 1 gumball = 0.74 - (0.92 - c)
Simplify to get: the cost of 1 gumball = c - 0.18

The total cost of 1 gumball and 1 chocolate bar is $1.24
We can write: (c - 0.18) + (c) = 1.24
Simplify: 2c - 0.18 = 1.24
Add 0.18 to both sides: 2c = 1.42
Solve: c = 1.42/2 = 0.71

Answer: E