You did not specify the brother's age, so I make a expression, <em>b</em> as the variable.
(3<em>b</em> + 5) - 11
Now do that with the brother age instead of the variable.
A mixed number looks like this: a(b/c)
The improper fraction currently looks like this: (ab/c)
Round the numerator to something you can divide by the denominator. For example, 45 would be rounded to 42. 42/7=6. 6 would be the whole number.
45-42=3. 3/7 is the new fraction.
So the answer for c is 6(3/7)
Do you know how to do d?
4 sin^2 θ + 13cos^2 θ = 7
sin^2 θ = 1 - cos^ θ
4 - 4cos^2 θ + 13cos^2 θ = 7
9cos^2 θ = 3
cos^2 θ = 1/3
cos θ = # (1/3) # - square root
Square root of (1/3) has +1/3 and -1/3 as values of cos
Find the key angle by doing the cos inverse of #1/3
K.A = cos^-1 #(1/3) = 0.955
θ lies in all 4 quadrants
The values of θ are:
θ = 0.955, 2.186, 4.096, 7.23
Ignore 0.955, 2.186, 4.096, 7.23 as they are out of range pi/2 = 1.571
The the value of θ = 0.955 = 0.96 (to 2 d.p) radian
Hope it helped!