three years hence, a man's age will be three times his brothers age, and the sum of present age is 18.find their present age​

Older brother = 15

Younger brother = 3

Step-by-step explanation:

Let the present age of the older brother = x

Let the present age of the younger brother = y

x + 3 = 3(y+ 3)          Remove the brackets

x + 3 = 3y +9

x + y = 18                  Solve for x

y = 18 - x                   Put this value into the top equation

x + 3 = 3(18 - x) + 9

x + 3 = 54 - 3x + 9

x + 3 = 63 - 3x          Add 3x to both sides

x + 3x + 3 = 63         Subtract 3 from both sides. Combine the xs

4x = 63 - 3

4x = 60                     Divide by 4

4x/4 = 60/4

x = 15

x + y = 18

15 + y = 18

y = 3

∠acb = 8°

step-by-step explanation:

∠xba lies on the circle and is half the measure of the intercepted arc ax

hence

measure of arc ax = 2 × 42° = 84°

∠acb is outside the circle and is

∠acb = (arcab - arcax ), hence

∠acb = 0.5 (100 - 84) = 0.5 × 16° = 8°