\fdO'^ - Old Forge Coal Mines

(246)
Then,-^ X
ALGEBRA. 131
Let X = speed of one.
4r + 10 = speed of other.
1,200
;r+ 10
= number of hours one train required.
= number of hours other train required.
1,200 _ 1,200
X ~ ;ir + 10
+ 10.
l,200.jr + 12,000 = 1,200^ + 10.t:' + lOOx
— 10.r' — 100.r = — 12,000.
10-ir' + 100A'= 12,000.
;ir' + 10^:= 1,200.
;r» + 10^ + 25 = 1,200 + 25 = 1,225.
^ + 5 = ± 35.
(247) 2^-^^—-? -4=0
5
3y + ^^-9 =
4r = 30 miles per hour.
;r + 10 = 40 miles per hour. [ Ans.
cleared of fractions, becomes
10^-j^+3-20 = 0. (1)
9y + X - 2 - 27 = 0. (2)
Transposing and uniting, 10.f — j=17. (3)
;ir + 9j = 29. (4)
Multiplying (4) by 10 and subtracting (3) from the result,
i0.ir+90j=290
y)x- y= Yt
91j = 273
y — Z. Ans.
Substituting value of ^ in •
(4),
;r+27 = 29.
;r = 2. Ans.
(248) {a) v^ X (^ = 2* X 3*. (Art. 547.)
2* X 3* = "V^ X ''(/F= f/32 X 27 = '^'864.
Ans.