How much of her long can she mow in 1 hour?

X = 0.5 of her lawn

Step-by-step explanation:

If

1/4  ---> 1/2 hour

X?  > 1 hour

Then

X = [1*(1/4)] / 1/2

X = 0.5 of her lawn

Best regards

Explanation:

Let's make A = 105 the given angle. The side opposite this is 'a'

The two given sides are b = 18 and c = 15

Use the law of cosines to find side 'a'

a^2 = b^2 + c^2 - 2*b*c*cos(A)

x^2 = 18^2 + 15^2 - 2*18*15*cos(105)

x^2 = 324 + 225 - 540*cos(105)

x^2 = 324 + 225 - 540*(-0.258819045102521 )

x^2 = 324 + 225 + 139.762284355361

x^2 = 688.762284355361

x = sqrt(688.762284355361)

x = 26.2442809837755

x = 26.2

Side note: make sure your calculator is in degree mode.