91Ó°ÊÓ

In the following exercise, simplify the expression:$(1-8)-(2-9)$

In the following exercise, simplify the expression:$-(6-8)-(2-4)$

In the following exercise, simplify the expression:$-(4-5)-(7-8)$

In the following exercise, simplify the expression:$25-[10-(3-12\left)\right]$

In the following, round to the indicated place value.

Round to the nearest ten.

$\left(a\right)386\left(b\right) 2,931$

In the following exercise, simplify the expression:$32-[5-(15-20\left)\right]$

In the following exercise, simplify the expression:$6.3-4.3-7.2$

In the following exercise, simplify the expression:$5.7-8.2-4.9$

In the following exercise, simplify the expression:$5^2-6^2$

In the following exercise, simplify the expression:$6^2-7^2$