If s - 8t + 20 = 5s - 7t + 1 = 0, then the value of s + t, to the nearest tenth, is ?

Read the following two statements. then use the law of syllogism to draw a conclusion. if the tv is too loud, then it will give me a headache. if i have a headache, then i will have to rest.

The length of a rectangle plus its width is 25 cm. the area is 156 square cm. what are the length and width of the rectangle? separate the answers with a comma.

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.