Question 956313
his average is now 10/18.


he wants to bring it up to 80%.


he will toss another x times.


since his average needs to be 80%, and since 80% is the same as .8 which is the same as 8/10, then:


(x + 10) / (x + 18) = 8/10


to solve this euatio0n, do the following:


cross multiply to get:


10 * (x + 10) = 8 * (x + 18)


simplify to get:


10x + 100 = 8x + 144


subtract 8x from both sides of the equation and subtract 100 from both sides of the equation to get:


10x - 8x = 144 - 100


simplify to get:


2x = 44


divide both sides of the equation by 2 to get:


x = 22


that's your solution.


(10 + x) / (18 + x) becomes (10 + 22) / ( 18 + 22) which becomes 32/40.


multiply 32/40 by (1/4) / (1/4) to get 8/10 is the same as .8 which is the same as 80%.