Answer
29.62 in
Work Step by Step
To find the final reading on the barometer, add each amount by which the mercury rises and subtract the amount by which the mercury falls.
$29.8+0.02-0.09-0.18+0.07\longrightarrow$ use commutative property to group positive and negative numbers together
$=29.8+0.02+0.07+-0.09+-0.18\longrightarrow$ add the positive and the negative addends
$=29.89+(-0.27)$ add
$=29.62$
