Answer:
20. 2x+y
21. 4
22. x+y
Explanation:
20. 9x+2y - x-2y find your LCM
4 4
=(9x+2y)-(x-2y) clear bracket
4
=9x+2y-x+2y collect terms
4
=9x-x+2y+2y
4
=8x+4y factorize
4
=4(2x+y)
4
=2x+y
with this, you will understand the following
21. 4x + 8y
x+2y x+2y
=4x+8y
x+2y
=4(x+2y)
x+2y
=4
22. 2x-y + 2x+5y
4 4
=2x-y+2x+5y
4
=4x+4y
4
=4(x+y)
4
=x+y