$25 with a 300% increase

100 dollars

Step-by-step explanation:

So amount of increase = (300/100) * 25

                                      = 3 * 25

                                      = 75 dollars

Then the final amount = (25 + 75) dollars

                                  = 100 dollars

∠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°