更新1:
this is a maths question but I don't know how to change the category , can someone please help me figure it out
in 11 years time , brain and matts ages will sum up to 100 .18 years ago brian was twice the age of matt. how old is brian now?
回答 (2)
2015-07-31 12:58 pm
Let the present age of Brian be x and Matts be y
In 11 years, Brian will be x+11 and Matts will be y+11
(x+11) + (y+11) = 100
x+y+22=100
x+y = 78 --------------(1)
18 years ago, Brian was x-18 and Matt was y-18
x-18 = 2(y-18)
x-18 = 2y-36
x-2y = -18 -------------(2)
subtract (2) from (1)
3y = 96
y = 32 (Matt's age)
x+y = 78
x+32 = 78
x = 78-32 = 46 (Brian's age now)
In 11 years, Brian will be x+11 and Matts will be y+11
(x+11) + (y+11) = 100
x+y+22=100
x+y = 78 --------------(1)
18 years ago, Brian was x-18 and Matt was y-18
x-18 = 2(y-18)
x-18 = 2y-36
x-2y = -18 -------------(2)
subtract (2) from (1)
3y = 96
y = 32 (Matt's age)
x+y = 78
x+32 = 78
x = 78-32 = 46 (Brian's age now)
2015-07-31 12:53 pm
32?
收錄日期: 2021-04-20 15:54:00
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