Answer:
x = 10.8
Explanation:
We can use the law of sines to solve this problem
sin A sin B
--------- = ----------
a b
sin 81 sin 40
--------- = ---------
x 7
Using cross products
7 sin 81 = x sin 40
Solving for x
7 sin 81 / sin 40 =x
x=10.75599
Rounding to 1 decimal place
x = 10.8