Answer:
10
Step-by-step explanation:
<u><em>y = -4 </em></u>
<u><em>x = 6 </em></u>
<em><u>x-y = 6-(-4) = 6+4 = 10</u></em>
<em><u /></em>
3x=21
x=21/3
x=7
hope it helps