Hello from MrBillDoesMath!
Answer:
a = 15
Discussion:
Division precedes subtraction ( order of operations) so
a/3-1 =4 => is equivalent to
(a/3) - 1 = 4 => add 1 to both sides
(a/3) - 1 + 1 = 4 + 1 = 5 => multiply both sides by 3
(a/3)* 3 = 5*3 = 15 =>
a = 15
Thank you,
MrB