Select all the system of equations that have exactly one solution A- y=2x+1
y=x+2

B- -x+10
-x+12

C- y=3x+1
y=3x+7

D- y=4x
y=x-6​

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 slope of any line parallel to the line 8x+9y=3 in the standard (x, y) coordinate plane?

Astock has a 25% probability of increasing by $10 and a 75% probability of decreasing by $5. what is the stocks expected increase or decrease?