1 glove costs $48
5 gloves cost $240 (since 5*48 = 240)
1 bat costs $35
b bats cost 35*b dollars, where b is some positive whole number
The total cost of the bats and gloves is 35*b + 240. We simply add the subtotals (240 from the gloves and 35*b from the bats)
Plug in b = 3 and use PEMDAS to evaluate
35*b + 240
35*3 + 240 .... b has been replaced with 3
105 + 240
345
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To summarize:
The cost expression is 35*b + 240 (the cost is in dollars)
The total cost if the coach bought three bats is 345 dollars