數學應用題。（eng.）

1. In Beijing, the temperature in the morning is 5℃. In the afternoon, the temperature rises by 2℃. At night, the temperature falls down to - 10℃. Find the difference between the temperature in the afternoon and at night.
The temperature in the afternoon =5 2=7℃
the difference between the temperature in the afternoon and at night.
=7-(-10)
=17℃

2. Ann has an Octopus card with an amount of $13. She buys some fast food which costs $22. Then she re-loads the card with $100. What is the amount on the card now?
the amount on the card now
=13-22 100
=$91
3.By the method of substitution, find the values of the following expressions if X = 3 and Y = 5.
(a)
[4(3) 3(5)]/2(3)(5)=0.9
(b)
(5)/(3 1) (3)/(5 1)=1.75
(c)
[(3)(5) 1]/(3-1) (3 1)(5)/(5-1)=13
4. Slove the following equations for x if m =9, n =2 and 1 =7.
(a)
3x=2 1
x=1
(b)
9-x=1
x=8
(c)
4x-3=9
4x=12
x=3
(d)
2(x-1)=9
x-1=4.5
x=5.5
(e)
2x 3=3(9)-4(2)=19
2x=16
x=8
(f)
(9 2 7)/x=9-1 2
18/x=10
x=1.8
5. A car is travelling at a speed of v m/s.
(a) What is the distance travelled by the car in t seconds?
the distance=vt m
(b) Find the distance travelled by the car at a speed of 210 m/s in one and a half minutes.
the distance=(210)(60 30)=18900m
6. The area of a parallelogram is equal to the area of a triangle. The height of the triangle is 5cm. If th two figures have the same base, find the height of the parallelogram.
Let the height of the parallelogram be h cm and their bases be b cm.
The area of a parallelogram is equal to the area of a triangle
bh=(5)b/2
h=2.5