Can somebody help me solve these questions?

Q1:If Tom buys 4 identical pairs of slippers,he will have $9 left.

If he buys 7 identical pairs of slippers,he will be short of $45.

How much does he have?

Q2:Mrs Chan had some bookmarks.She gave 50% of the bookmarks to her sister and 10% of the remainder to her brother and the rest to 5 children.

If each child receives 36 bookmark,how many bookmarks did she have at first?

Q3:There are 8 people in a room.If every person shakes hands with every other person,

how many handshakes are there altogether?

Q4: Terrence's age is 3\8 that of Sabrina's age.Candice's age is 2\9 that of Terrence's age.Find the ratio of Candice's age to Sabrina's age?

Q5:40% of Paul's age is the same as 25% of James' age.Their total age is 130 years.Find Paul's age in 20 years' time.

For those who will be helping me to solve these questions,thanks in advance.