plisss bantu jawabbb donggg untuk nomor 7&8

7. 2B-3A
= 2(3x+4y)-3(2x-5y)
= 6x+8y-6x+15y
= 6x-6x+8y+15y
= 23y (C)

8. Kell ∆ = s+s+s
= (2a-1)+(20-a)+(3a-5)
= 2a-1+20-a+3a-5
= 2a-a+3a-1+20-5
= 4a+14 (A)