Answer:
a) 1.8 
b) 3.6 
Step-by-step explanation:
Conversion and calculation of areas
The area of a rectangle is A=wh, where w is the width and h is the height. There are 3 feet in one yard
a)
We are told Kalie put 6 stickers, each one of 1/2 centimeters (0.5 cm) wide by 3/5 (0.6 cm) centimeter long. The area of one sticker is
A=(0.5)(0.6)=0.3 
Assuming there is no overlapping, the 6 stickers have a total area
6*0.3
=1.8 
b)
Each of Elana's wrapping papers measures 2/5 yards long and 1/4 yard wide. Converting them to feet we have
long=2/5*3=1.2 feet
wide=1/4*3=0.75 feet
Area of each paper=1.2 feet*0.75 feet=0.9 
Area of the entire board, assuming no overlapping and no space left uncovered=4*0.9 
Area of board=3.6 
Let Tina bought X number of nail polish any Y number of lip gloss.
then, X+Y=9
or,X=9-Y
Also,4.5 X+7 Y=50.5
or, 4.5 (9-Y) +7 Y=50.5
or, Y =4.........................................(i)
so, X= 9-4
= 5........................................(ii)
hence, she bought 5 nail polish and 4 lip gloss
12(3x+4)-5(2x-6)=6x-22
36x + 48 - 10x + 30 = 6x - 22
26x + 48 + 30 = 6x - 22
26x + 70 = 6x - 22
20x + 70 = -22
20x = -92
x = -4.6