Example on worksheet (subtracting by adding up)
50-29?
29+20=49
49+1=50
20+1=21
50-29=21
My question is where did the 20 come from? can you help me understand this?

Evaluate 4 a for a = 5 2/3 . express your answer in simplest form.

Which ahows the graph of the solution set of 6x+4y< 12

Which is a true statement comparing the graphs of x^2/6^2-y^2/8^2 = 1 and x^2/8^2-y^2/6^2 the foci of both graphs are the same points. the lengths of both transverse axes are the same. the directrices of = 1 are horizontal while the directrices of = 1 are vertical. the vertices of = 1 are on the y-axis while the vertices of = 1 are on the x-axis.