It takes 250 g of pasta and 240 ml of sauce to make one batch of spaghetti and it takes 600g of pasta and 700ml of sauce to make one batch of lasagna.
Case 1: Pasta
The chef wants to make spaghetti and lasagna using more than 4000 g of pasta.
S denote the number of batches of spaghetti he makes and L the number of batches of lasagna he makes.
So the equation becomes :

Case 2: Sauce
chef wants to make spaghetti and lasagna using more than 5000 ml of sauce.
S denote the number of batches of spaghetti he makes and L the number of batches of lasagna he makes.
So the equation becomes:
Answer :
The two equations are :
For pasta: 
For sauce:
The answer is 58/100 or 29/50ths
1) the answer is 5x and -2x
2) -3a and a
3)4x and 5x
4)7x
The straight arrow at the bottom represents 180 degrees.There 3 x's in eqaution so you divide 180 by 3 and you get 60 degrees