x + 0.07x = 45; x = $42.06
if x is the basic price we must add 7% to this. As a fraction 7% is 7/100. As a decimal number this is 0.07, so the total to be paid is x + 0.07x (which can also be written as 1.07x). This must equal $45, so 1.07x = 45; divide both sides by 1.07 to get:
$42.06 to the nearest penny.
Hope this helps!