Answer:
A=1.75
Step-by-step explanation:
[tex]10a + 6a = 21 + 7 \\ 16a = 28 \\ divide \: both \: sides \: by \: 16 \\ a = 1.75 \: or 1 \ \frac{3}{4} [/tex]
a = 7/4
10a -7 = 21 - 6а
Add 6a to each side
10a+6a -7 = 21 - 6а+6a
16a -7 = 21
Add 7 to each side
16a+7-7=21+7
16a = 28
Divide each side by 16
16a/16 = 28/16
