Answer
$18y+7$
Work Step by Step
Commutative properties: $a+b=b+a,\qquad ab=ba$
Associative properties:$ a+(b+c)=(a+b)+c,\qquad a(bc)=(ab)c$
Distributive property: $\quad A(x+y)=Ax+Ay$
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$ 8y+7+10y=\qquad$
...commutative property: $7$ and $10y$ can change places
$=8y+10y+7=$
...associative property: we can add any pair we like, first
$=(8y+10y)+7$
... combine like terms,
= $18y+7$
