Answer: A
Step by Step: to isolate 7x, subtract 15 from both sides of the equation. 15-15=0. 38-15=23.
now the equation is 7x=23
finally, to completely isolate the variable, divide 7 from both sides. 7x/7= x. 23/7=23/7 because it cannot be simplified further unless you want it to be a decimal.
so the answer is A, 23/7