Question

If the operation # is defined by the equation x # y = 2x + y,what is the value of a in the equation 2 # a = a # 3 ?

a. 0
b. -1
c. 1
d. 1.5
e.-1.5
f. 2

Answer 1

just plug in the numbers:
2#a = 2*2+a
a#3 = 2a+3

so, now we have

4+a = 2a+3
a = 1