87.5 percent
Reason: 40/40-5/40 is 35/40. Divide 35/40 and you get 0.875. Multiply by a hundred and you get 87.5%
cos(20) = sin(70)
note how 20+70 = 90
The general rule is that if x+y = 90, then cos(x) = sin(y). The rule works in reverse as well. Another way to phrase the rule is cos(x) = sin(90-x).
So,

Note: if the computer doesn't like the answer of "sin 70" then try "sin(70)" and see how that works out. It's also possible that the teacher wants the single numeric value of "70" in the first box rather than the "sine" part to go along with it. Though that would be strange and incorrect since cos(20) = 70 is a false statement.
Every hour, the number of liters decreases by 0.5 liter.
The graph is a function. When drawing a vertical line, there will be two circumstances:
- The line intersects only one point on a graph.
- The line intersects more than one point on a graph ( POI > 1 )
For the first circumstance, the graph that has only one intersect with a line - it is a function. For the second circumstance, the graph cannot be a function as it gives more than one y-value for a single x-value.
The conclusion is that if a line only has one intersect on a graph then it is a function. Otherwise, not a function but a relation instead. All functions are relations, but not all relations can be functions.
Answer
- The graph passes the vertical line test and is a function.