Question

A gambler begins playing a slot machine with $10 in quarters in her coin bucket. She plays 15 quarters before winning a jackpot of 50 quarters. She then plays 20 more quarters in the same machine before walking away.

How many quarters does she now have in her coin bucket?

Answer 1

We first figure out how many quarters she starts

with. Four quarters per dollar gives you 4 · 10

= 40 quarters. We can write an expression that

represents the quarters in the bucket and the

quarters added and subtracted. In chronological

order, the expression would be as follows: 40 − 15 + 50 − 20

we Change all operation signs to addition and

the sign of the number that follows. 40 + −15 + 50 + −20

Because addiction is commutative, we can

associate like-signed numbers. (40 + 50) + (−15 + −20)

Use the rules for adding integers with like

signs. [40 + 50 = 90]

[−15 + −20 = −35]

Substitute into the revised expression. (90) + (−35) = 55

we obtain expression as follows: 40 + −15 + 50 + −20 = 55

the expression is as follows: 40 + −15 + 50 + −20 = 55