Quadrilateral EFGH with diagonals EG and HF must be a parallelogram if (1) EF FG  and GH HE  (2) EG FH  (3) EG FH  (4) EF HG  and EF HG 

EF = HG and EF || HG

Step-by-step explanation:

A quadrilateral is a polygon shape with four sides and four angles.

A parallelogram is a quadrilateral with two pairs of parallel sides. The following are properties of a parallelogram:

If Quadrilateral EFGH with diagonals EG and HF is a parallelogram then EF = HG and EF || HG

The answer is in the image 

The answer is in the image 

For every 8 cars there are 7 trucks

Therefore,

Cars:Truck=8:7

Answer is B)8:7

The solution is in the following image

The answer is in the image 

The solution is given in the image below

Speed=Distance/time

Here,

distance=15m

time=1sec

speed=15/1=15m/sec

Distance=Speed*time

time=15min=15*60sec=900sec

Distance travelled in 15 min=15*900=13,500m

=13500/1000 km=13.5Km

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.