Define a variable and write an algebraic expression to model each situation:

1) what is the total cost of buying several shirts at $24.95 each?

2) the number of gal of water used to water trees is 30 times the number of trees.

3) what is the number of marbles left in a 48-marble bag after some marbles have been given away?

4) what is the cost of buying several pairs of pants at $32.95 per pain?

It is suitable to start with a "let ... " statement defining the meaning of the variable (s) you use in the problem. Here, problems 1, 2, 4 have you multiply the variable by some constant representing a unit rate. In problem 3, you additionally have to perform some math to find an amount remaining.

1) Let s represent the number of shirts purchased at 24.95 each. Then the total cost in dollars is ...

... 24.95s

2) Let t represent the number of trees watered. Then the total number of gallons of water used is ...

... 30t

3) Let q represent the quantity of marbles given away. Then the number remaining is ...

... 48 - q

4) Let p represent the number of pairs of pants purchased at 32.95 each. Then the total cost in dollars is

... 32.95p