How much pure acid should be mixed with 7 gallons of a 40% acid solution in order to get a 70% acid solution?

You are responsible for designing a new city. you are inspired by pierre charles l'enfant, who laid out the streets of our nation's capital. numbered streets run north and south, and lettered streets run east and west. avenues are named after states, and they intersect the streets on a diagonal. the streets are parallel and the intersections form similar triangles. 18th st. is 454 meters long and the intersection of 18th and k st. is 207 meters from connecticut ave. if 19th st. and k st. is 385 meters from connecticut ave., what is the length of 19th st.?

Amira is painting a rectangular banner 2 1/4 yards wide. the banner will have a blue background. amira has enough paint to cover 1 1/2 square yards of the wall. the school colors are blue and yellow, so amira wants to add yellow rectangles on the left and right sides of the blue rectangle. the yellow rectangles will each be 3/4 yards wide and the same height as the blue rectangle. what will be the total area of the two yellow rectangles?

What is the value of x? enter your answer in the box.