math (show steps), thank you! {quick!}

1. the cost of a book is $(a+1) and that of a pen is $(a+2). If the total cost of the book and the pen is $33, what is the value of a?
a+1+a+2=33
2a+3=33
a=15
2. Jenny's father is now 35 years old. Five years later, he will be 4 times as old as Jenny then. how old is Jenny now?
let Jenny now is x years old
Five years later
Jenny now is x+5 years old, his father is 40 years old
At that time, Jenny father will be 4 times as old as Jenny then
4(x+5)=40
x=5
Jenny now is 5 years old
3. The amount donated by Mr Lee each month is $1/4(I - 8000), where I stands for his monthly income. If Mr Lee donated $500 in July, find his income in that month.
1/4(I - 8000)=500
I - 8000=2000
I=10000
his income in that month is 10000

1.)(a+1)+(a+2)=33
a+1+a+2)=33
2a+3=33
2a=30
a=15
唔知你no2.ask what....我諗ans is 5
唔知你no3.ask what.....sor~

1. the cost of a book is $(a+1) and that of a pen is $(a+2). If the total cost of the book and the pen is $33, what is the value of a?
(a+1)+(a+2)=33
2a+3=33
2a=30
a=15

2. Jenny’s father is now 35 years old. Five years later, he will be 4 times as old as Jenny then. how old is Jenny now?
let Jenny is x years old now
35+5=4(x+5)
x+5=10
x=5
so Jenny is 5 years old now.

3. The amount donated by Mr Lee each month is $1/4(I - 8000), where I stands for his monthly income. If Mr Lee donated $500 in July, find his income in that month.
1/4(I-8000)=500
I-8000=2000
I=10000
so his income of this month is $10,000

1. ( a+1 ) + ( a + 2 ) = 33
2a + 3 = 33
a = 15


2. Let Jenny x year old now


4 ( x+ 5 )= 35 + 5
4x + 20 = 40
x= 5

Jenny is 5 years old

3. 1/4 I - 2000 = 500
I = 2500 * 4
I =10000