She will need 172 cups of water for 1 cup of lemon mix
To make the lemonade, 43 cups of water are required for 1/4 cup of lemon mix
This means that x cups of water will be required for 1 cup of lemon mix
To get x, we simply proceed to multiply;
43 * 1 = x * 1/4
43 = x/4
x = 43 * 4
x = 172 cups of water