if you mean a number when multiplied by -15 will give you +2, then the answer is
-15 times x=2
divide both sdies by -15
x=2/-15=-1/7.5
x=1/7.5
or if you mean what 2 number multily to get -15 and add to get 2, then the numbers are -3 and 5
when multiplied they give-15
when added together they give 2
