i'm sorry but can you put in more details as to what each item costs, if it is just variables then it should be something like b times the amount bought plus c times the amount bought. without the costs i cannot actually give you how much she spent
X=12.5
If the perimeter is 90
90=3x+3x+15
Combine like terms
90=6x+15
Subtracts 15 from both sides
75=6x
Divide by six to get x by itself
12.5=x
Does this help?
A-10......C-he didn't notice that a domino has number that will equal 49 in multiplication but will not add up to be if its less than 4 dominos
First, divide the percent by 100. Then if the percent is not a whole number, then multiply the top and bottom by 10 for every number after the decimal point. :)