Need some help with some questions:

1) The sum of the digits of a two - digit are reversed the number is increased by 36. Find the number by solving a pair of simultaneous equations.

2) 3 bags and 4 pens cost $61, whereas 4 bags and 3 pens cost $63.60. Find the cost of a bag and 10 pens.

3) Two runners start from the same point at the same time. They will 4km apart at the end of 2 hours if they are running in opposite directions. Let x be the speed of the faster runner and y be the speed of the slower runner.

i. Write down a pair of simultaneous equations using the fact that distance = speed×time.

ii. Find their speeds.