I didn’t spend all weekend playing music. I also spent some time in the garden, including constucting a free-standing shelf for the polytunnel:

One of the challenges was figuring out where to put the horizontal supports. I couldn’t just lay it out on the ground as I needed to include the height of the racking and trays to figure out whether we could get four levels with reasonable clearance. That provide a rare opportunity to use some algebra. I wanted to figure out what clearance — x — I would get with four bays of shelving. The combined height of support, rack and average plant try was 13cm and the total height of the shelving was about 144cm. That meant I could find my answer by solving 4(x +13) = 144; that results in x = 23cm or, in practical terms, plenty of working height.

It still took a bit of measuring, cutting, drilling, screwing and banging and a chunk of time to reach the end result but at least, by dipping back into elementary algebra, I knew I wouldn’t end up running out of room.