What is the value of b in the equation b + 8 = 13? 5 8 13 21

I’m stuck on this i don’t understand.

Me #1 using vocabulary words, including the word “congruent”, state why the measure of angle d is 120 degrees. #2 what is the measure of angle e and why?

Two blends of tea are mixed to make a blend that will be sold at the fair. black tea sells for $2.20 per pound and orange pekoe tea sells for $3.00 per pound. how much of each should be used to obtain a 4lb blend selling for $2.50 per pound?