For this equation :

a+5= -7

what is the answer?

Hey! a+5=7 means that a is the variable, while seven is the answer. My technique is like this: 7-5=2 You need to subtract the numbers you already have. This only works for addition! Hope this helps :) !

If i think this is what your asking, he should look at the grams or pounds/ounces and compare the to their cost then max can identify which one is proportional and which is not ( i think xd)