3-3x6+2= we have 3 answers so far -17 -13 2 any idea's on which is correct

Dakota earned $7.50 in interest in account a and $18.75 in interest in account b after 15 months. if the simple interest rate is 4% for account a and 5% for account b, which account has the greater principal? explain. to make it a little easier, there is an image. good luck!

What is the value of n in the equation -1/2(2n+4)+6=-9+4(2n+1)

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18