Can someone pretty me solve 1) a & b?

STEP 1:
find the decimal version of the tax rate

x= tax rate

cost of item * x= tax total

$340x= $10.20
divide both sides by 340

x= 10.20/340

x= 0.03

STEP 2:
find the percent version of the tax rate; multiply decimal version by 100 (or simply move the decimal two places to the right)

= 0.03 * 100
= 3%

CHECK:
$340 * 3%= $10.20
340 * 0.03= 10.20
10.20= 10.20

ANSWER: The tax rate is 3%.

Hope this helps! :)