we have the expression
y+1.2y+1.2z
there are three terms ----> y, 1.2y, and 1.2z
the like terms are y and 1.2 y (have the same variable y)
Part 2
we have the expression
2+7*-5*9
Applying PEMDAS
P ----> Parentheses first
E -----> Exponents (Powers and Square Roots, etc.)
MD ----> Multiplication and Division (left-to-right)
AS ----> Addition and Subtraction (left-to-right)
so
solve multiplication first
(7)*(-5)*(9)=-315
substitute
2+(-315)
adds the numbers
2-315=-313
the answer is -313