#### Answer

$21$

#### Work Step by Step

Solve using PEMDAS (The priority list for solving expressions: Parentheses, exponents, [multiplication, division], [addition, subtraction]. For the operations in the brackets, solve from left to right)
$3\cdot 4 + 9\cdot 1 = 12 + 9\cdot 1 = 12 + 9 = 21$