$1.$ Adobe Inc. reported the following for the current year.

ADOBE INC.

Consolidated Income Statement

$12$ Months Ended $($$ millions$)$

Current Year

Prior Year

Two Years Prior

Revenue

$$ Subscription

$$16,388$

$$14,573$

$$11,626$

$$ Product

$532$

$555$

$507$

$$ Services and other

$686$

$657$

$735$

Total revenue

$17,606$

$15,785$

$12,868$

Cost of revenue

$$ Subscription

$1,646$

$1,374$

$1,108$

$$ Product

$35$

$41$

$36$

$$ Services and other

$484$

$450$

$578$

Total cost of revenue

$2,165$

$1,865$

$1,722$

Gross profit

$$15,441$

$$13,920$

$$11,146$

a$.$ Determine the overall gross profit margin for each year.

$$

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b$.$ Which type of revenue has the highest gross profit margin in the current year?