At a bicycle shop, a bicycle costs $49 and a tricycle costs $27. An after-school club buys bicycles and tricycles with a total of 39 wheels. The club buys 2 more bicycles than tricycles. a. How many bicycles does the club buy?

Let b for the number of bicycles, and t for the number of tricycles.

2b+3t=39 (a bicycle has 2 wheels and a tricycle has 3 wheels)

b=t+2 = >t=b-2

substitute b for t: 2b+3 (b-2) = 39

2b+3b-6=39

5b=45

b=9

the club buys 9 bicycles and 7 tricycles.