Solve for x and y
x+y=a
x−y=b
PLZ HELP VERY URGENT

3.4a=57.8 what is the the value of a

Maci and i are making a small kite. two sides are 10". two sides are 5". the shorter diagonal is 6". round all your answers to the nearest tenth. 1. what is the distance from the peak of the kite to the intersection of the diagonals? 2. what is the distance from intersection of the diagonals to the top of the tail? 3. what is the length of the longer diagonal?

Ellie spent $88.79 at the computer stote. she had $44.50 left to buy a cool hat. how much money did she originally have? write and solve an equation to answer the question.