Answer:
- 5·$3.50 +4d = $163.50
- d = $(163.50 -5·3.50)/4 = $36.50
Step-by-step explanation:
The total purchase amount is the sum of the products of the cost of an item times the number of that item. For 5 items costing $3.50 each and 4 items costing "d" each, the total purchase amount is ...
5·$3.50 +4·d = $163.50
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This is solved by undoing what is done to the variable. The variable is multiplied by 4 and a quantity added to that product. We undo these operations in reverse order.
First we subtract the added quantity:
4d = $163.50 -5·3.50 = $146.00
Then we undo the multiplication by dividing by the coefficient of d:
4d/4 = $146.0/4
d = $36.50
The cost of one pair of shoes is $36.50.
