apologiabiology: what they want you to do is subsitute 3 for d
write 3 for everywhere you see d and remember that 3d means 3 times d and -d means -1 times d
(d+3d)-(-d+2)
d=3
(3+3(3))-(-3+2)
(3+9)-(2-3)
(12)-(-1)
12+1
13
answer is 13
Do you like cookies? ♥ We use cookies to ensure you get the best experience on our website. Learn more