Answer:
Hello! answer: r = 7
Explanation:
Hi im sorry I will try to explain this the simplest way possible! so all of this will add up to 180 we know 1 angle is 55 and the 1 that isnt labelled is 90 because its a complementary angle leta add those and subtract so we can figure out what our last angle will have to equal so... 55 + 90 = 145
180 - 145 = 35 so now we know the last angle will have to equal 35 r is just a place holder its just representing something multiplied by 6 subtracted by 7 will equal 35 so...
6 × 7 = 42 and 42 - 7 = 35 So 7 is r!! Hope that helps!