Mari needs 2 yards of scrap cloth. she finds five 1/2 yard pieces does she have enough cloth

Ametalworker has a metal alloy that is 30? % copper and another alloy that is 55? % copper. how many kilograms of each alloy should the metalworker combine to create 90 kg of a 50? % copper? alloy?

What is the answer to this question? i'm a bit stumped. also how do i do it? 5(x - 4) = 2(x + 5)

The suare root of 9x plus 7 plus the square rot of 2x equall to 7