The complete question is as follows.
The equation a =
can be used to determine the area , <em>a</em>, of a trapezoid with height , h, and base lengths,
and
. Which are equivalent equations?
(a) 
(b) 
(c)
= 
(d) 
(e)
= h
Answer: (a)
; (d)
;
Step-by-step explanation: To determine
:
a = 
2a = (
)h


To determine h:
a = 
2a = 
= h
To determine 
a = 
2a = 


Checking the alternatives, you have that
and
= h, so alternatives <u>A</u> and <u>D</u> are correct.
The problem is 3+6x = 15 with x being the number of white numbers.
Isolate variable by subtracting 3 on both sides: 6x = 12.
Isolate variable by dividing 6 on both sides: x = 2
The number of white marbles is 2.