就1題,麻煩各位>_<''20分

Let x be the large globe and y be the small globe.

So, 3x+2y=6600 --(1)
and 2x+3y=5900--(2)

then (1): 3x=6600-2y
x=(6600-2y)/3 --(3)

Put(3) in (2) : 2{(6600-2y)/3} +3y=5900
..
..
..
y=900 and x=1600

So, Mr Lee should pay x+y=900+1600=$2500.

let a be the price of the large globe .
let b be the price of the small globe .

3a+2b=6600 . . . 1
2a+3b=5900 . . . 2

from 1
3a+2b=6600
3a=6600-2b
a=2200-(2/3)b . . . 3

sub 3 into 2
2a+3b=5900
2(2200-(2/3)b)+3b=5900
4400-(4/3)b+3b=5900
(5/3)b=1500
b=900
sub b=900 into 1
3a+2(900)=6600
3a=4800
a=1600

a+b
=1600+900
=2500
If mr Lee buys 1 large and 1small globes from this shop,he should pay $2500.

Let LARGE GLOBES be 'L'
Let SMALL GLOBES be 'S'

3L + 2s = $6600....(1)
2L + 3S = $5900....(2)

From (1):
2S=6600-3L
S=(6600-3L)/2....(3)

Sub (3) into (2)
2L + 3((6600-3L)/2)=$5900
2L+((19800-9L)/2)=5900
(4L+19800-9L)/2 = 4900
19800-5L=11800
8000=5L
L=1600

Sub L into (3)
S=(6600-3(1600))/2
S=900

Mr Lee wants to buy 1 large and 1 small globes
hence:
1L+1S=1(1600) + 1(900)
=1600+900
=$2500