40=5d-10
first, you have to multiply 5 by D and-2 and then , you will get 40=5d-10
then you will combine like terms, like 40+10=5d
then you will get 50=5d and you divide 50 by 5 to get D only, and finally, you will get D=10.
the final answer is D=10
second question,
all you have to do is multiply-2 by x and -9
and then you get -2x+18=-24
then, you have to combine like terms like I did on the first one, which is -2x= -24-18 and then, you will get -2x=-42 and you have to divide 2 by -42 which is x=21
the final answer is x=21.
I am pre sure that it helped you. text me on messages on brainy if you have any questions that you want to ask me.