Answer
0.6
Work Step by Step
First, we simplify the expression:
$-3a-1+7a-2$
=$-3a+7a-1-2$
=$4a-3$
We evaluate the expression by substituting the value of $a=0.9$ into the expression:
$4a-3$
=$4(0.9)-3$
=$4(\frac{9}{10})-3$
=$\frac{36}{10}-3$
=$\frac{36-3(10)}{10}$
=$\frac{6}{10}$
=$0.6$
