I hope this helps you
1/2-3/7
7.1/2.7-2.3/2.7
7/14-6/14
1/14
Cos10 cos20 -sin10 sin20 = cos(10+20) = cos30 = √3/2

Distribute

Combine like terms

Add 1 and subtract 6x from each side
0 = 12
The equation has no real solution
9(3+5)
if you go through each answer choice you will notice that none of the rest are right
8(3+6) = 24 +48
8(19 +37) = 152 + 296
9(18 +36)= 162 +324