All has $20 to spend each week and he can allocate that money between bus...

All has $20 to spend each week and he can allocate that money between bus tickets for getting to work and the burger he eats for lunch. Burgers cost $4 each, and bus tickects are $1 each.
1. What’s the equation of the budget constraint
2. Find the slope of the budget constraint
3. Interpret the slope of the budget constraint
4 Suppose Al’s town drops the price of bus tickets by half and the price of burgers also drops by half but his weekly spending money remains the same. What’s the equation of the new budget constraint ? How is the slope of the budget constraint affected by these two changes ?