Question

(\frac{2}{5}y - 4 + 7 - \frac{9}{10}y)

Explanation:

Step1: Combine like variable terms

First, convert $\frac{2}{5}y$ to a fraction with denominator 10 to combine with $-\frac{9}{10}y$:
$\frac{2}{5}y = \frac{4}{10}y$
$\frac{4}{10}y - \frac{9}{10}y = \frac{4-9}{10}y = -\frac{5}{10}y = -\frac{1}{2}y$

Step2: Combine constant terms

Add the constant values $-4$ and $7$:
$-4 + 7 = 3$

Answer:

$-\frac{1}{2}y + 3$